hello folks, I have quite a lot of cactus in my flat, and worring about their care, I've wondered if it would be a nice idea to give them a tan; so to put them under blacklight, near ultraviolet light to speed up growth and make then healtier, as they don't get that much sunlight during the winter. Any information or personal experience welcome Thank you all in advance
Cacti go dormant in the winter (in the northern hemisphere). I don't think giving them extra light will be a benefit. They are best left in a dry, cool (not freezing) place where there is some natural light.
I agree with the advice given by tumamoc. Plants do not use UV light for their photosynthesis. You will need a very strong light source in the visible region of the spectrum if you want to provide a useful amount of light. UV light affects things like skin color and spine length/thickness but is not essential, cactus growers typically grow their plants in greenhouses where the glazing blocks much of the UV. Too much UV can scorch your plants. Blacklight is, as I understand it, UVA (the weakest part of the UV range), so perhaps it is not too harmful. Scorching is a common problem for people like me who put their cacti outside in spring, we must be very careful with strong sunlight until the plants have developed their "tan". So, UV during other seasons is not necessary either, but beware if you put them in the sun (I assume that it is pretty strong in Arizona) after keeping them indoors for some time. Do not turn them 180° either, the "tan" develops only on the side facing the light source (I have seen what happens to the more tender species if you try that ...)
I could guess than that a lite, periodical tan of UVA might develop a protection for that widespread phenomenon of spring's burn; thank you all for sharing experience